Scanned MicroLED array for waveguide display

ABSTRACT

A waveguide display includes a source assembly, an output waveguide, and a controller. The source assembly includes a light source and an optics system. The light source includes source elements arranged in a 1D or 2D array that emit image light. The optics system includes a scanning mirror assembly that scans the image light to particular locations based on scanning instructions. The output waveguide receives the scanned image light from the scanning mirror assembly and outputs an expanded image light. In some embodiments, the waveguide display includes a source waveguide and the 1D array of source elements. The source waveguide receives a conditioned image light from the source assembly. The controller generates the scanning instructions and provides the scanning instructions to the scanning mirror assembly. In some embodiments, the controller provides the scanning instructions to an actuator assembly of the source waveguide.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/294,131, filed Feb. 11, 2016, which is incorporated by reference inits entirety.

BACKGROUND

This disclosure relates generally to near-eye-displays, and inparticular, to near eye displays including scanning MicroLED arrays.

In conventional display designs in near-eye-displays, the common factorsconsidered are brightness, resolution/FOV, and compactness. In augmentedreality (AR) applications using next generation displays, often awideband source is preferable than single wavelength laser. MicroLEDsare a good choice for such displays due to their wide spectrum and highbrightness. But the small array size in MicroLED technology limits asimple 2D display resolution to about 640×480. In addition, the displaysize is also large due to large pixel pitch and low fill factor of thearray.

SUMMARY

A waveguide display used as part of a virtual reality (VR) system, anaugmented reality (AR) system, a mixed reality (MR) system, or somecombination thereof. In some embodiments, the waveguide display may beincluded in an eye-wear comprising a frame and a display assembly thatpresents media to a user's eyes. The display assembly includes a sourceassembly and an output waveguide. The source assembly includes a lightsource which emits image light to the output waveguide which expands theimage light and outputs the expanded image light to the user's eyes. Insome embodiments, the display assembly includes the source assembly, theoutput waveguide and a source waveguide. The source waveguide is a longand narrow waveguide that expands the image light emitted by the sourceassembly to the output waveguide in one dimension.

The source assembly includes a light source, and an optics system. Acontroller controls one or more scanning components of the displayassembly. In some embodiments, the controller controls the scanning ofthe source waveguide, which outputs the image light toward the outputwaveguide. In some embodiments, the controller controls one or morescanning mirrors, which outputs the image light toward the outputwaveguide.

The light source includes one or more source elements (e.g., microLEDs).The one or more source elements may emit light in the same wavelengthrange (e.g., all emit the same color). Alternatively, some sourceelements may emit light at different wavelength ranges than other sourceelements (e.g., one source emits in red, another emits in blue, andanother emits in green). In some embodiments, a plurality of sourceelements forms an array. In some embodiments, the array is onedimensional, linear array of source elements. Alternatively, the arraymay be a two-dimensional array of source elements (e.g., a spare array).Additionally, in some embodiments, the array may be a curved array—whichmitigates field curvature. Additionally, in some embodiments, each ofthe plurality of source elements may be in contact with an opticalisolator (e.g., Aluminum film) that helps reduce optical interferencebetween adjacent source elements.

The optics system includes one or more optical elements that condition(e.g., expand and/or collimate) light received from the light source.The optics system may also include one or more scanning mirrors (e.g.galvanometer mirror, MEMS mirror) that scan light received from thecollimating lens. The one or more scanning mirrors may perform ascanning along one or two dimensions. The use of one dimensional arrays,sparse 2D arrays, and/or MicroLEDs also helps reduce design constraintsfor the scan angle and resonance frequency of the scanning mirrorassembly. The scanning mirrors emit the scanned light to the outputwaveguide, such that a scanned image is ultimately output from theoutput waveguide. In some embodiments, the optics system does notinclude the one or more scanning mirrors.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of a near-eye-display (NED), in accordance with anembodiment.

FIG. 2 is a cross-section of an eyewear of the NED illustrated in FIG.1, in accordance with an embodiment.

FIG. 3 illustrates an isometric view of a waveguide display, inaccordance with an embodiment.

FIG. 4 illustrates a block diagram of a source assembly with a 1Dsource, the source assembly outputting a scanned light, in accordancewith an embodiment.

FIG. 5 illustrates a block diagram of a source assembly with a 2Dsource, in accordance with an embodiment.

FIG. 6 illustrates an isometric view of a waveguide display, inaccordance with an embodiment.

FIG. 7 illustrates a cross-section of a scanning waveguide display, inaccordance with an embodiment.

FIG. 8 illustrates a block diagram of a source assembly with the 1Dsource, in accordance with an embodiment.

FIG. 9A illustrates an array with adjacent dies, in accordance with anembodiment.

FIG. 9B illustrates an array that includes an optical isolator, inaccordance with an embodiment.

FIG. 9C illustrates an array with non-adjacent dies, in accordance withan embodiment.

FIG. 9D illustrates a stacked array of three columns of 1D array, inaccordance with an embodiment.

FIG. 9E illustrates a 2D sparse array, in accordance with an embodiment.

The figures depict embodiments of the present disclosure for purposes ofillustration only. One skilled in the art will readily recognize fromthe following description that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles, or benefits touted, of the disclosure described herein.

DETAILED DESCRIPTION

FIG. 1 is a diagram of a near-eye-display (NED) 100, in accordance withan embodiment. The NED 100 presents media to a user. Examples of mediapresented by the NED 100 include one or more images, video, audio, orsome combination thereof. In some embodiments, audio is presented via anexternal device (e.g., speakers and/or headphones) that receives audioinformation from the NED 100, a console (not shown), or both, andpresents audio data based on the audio information. The NED 100 isgenerally configured to operate as a VR NED. However, in someembodiments, the NED 100 may be modified to also operate as an augmentedreality (AR) NED, a mixed reality (MR) NED, or some combination thereof.For example, in some embodiments, the NED 100 may augment views of aphysical, real-world environment with computer-generated elements (e.g.,images, video, sound, etc.).

The NED 100 shown in FIG. 1 includes a frame 105 and a display 110. Theframe 105 includes one or more optical elements which together displaymedia to users. The display 110 is configured for users to see thecontent presented by the NED 100. As discussed below in conjunction withFIG. 2, the display 110 includes at least one source assembly togenerate an image light to present media to an eye of the user. Thesource assembly includes, e.g., a source, an optics system, or somecombination thereof.

FIG. 1 is only an example of a VR system. However, in alternateembodiments, FIG. 1 may also be referred to as a Head-Mounted-Display(HMD).

FIG. 2 is a cross section 200 of the NED 100 illustrated in FIG. 1, inaccordance with an embodiment. The cross section 200 includes at leastone display assembly 210, and an exit pupil 230. The exit pupil 230 is alocation where the eye 220 is positioned when the user wears the NED100. In some embodiments, the frame 105 may represent a frame ofeye-wear glasses. For purposes of illustration, FIG. 2 shows the crosssection 200 associated with a single eye 220 and a single displayassembly 210, but in alternative embodiments not shown, another displayassembly which is separate from the display assembly 210 shown in FIG.2, provides image light to another eye 220 of the user.

The display assembly 210, as illustrated below in FIG. 2, is configuredto direct the image light to the eye 220 through the exit pupil 230. Thedisplay assembly 210 may be composed of one or more materials (e.g.,plastic, glass, etc.) with one or more refractive indices thateffectively minimize the weight and widen a field of view (hereinafterabbreviated as ‘FOV’) of the NED 100. In alternate configurations, theNED 100 includes one or more optical elements between the displayassembly 210 and the eye 220. The optical elements may act to, e.g.,correct aberrations in image light emitted from the display assembly210, magnify image light emitted from the display assembly 210, someother optical adjustment of image light emitted from the displayassembly 210, or some combination thereof. The example for opticalelements may include an aperture, a Fresnel lens, a convex lens, aconcave lens, a filter, or any other suitable optical element thataffects image light.

In some embodiments, the display assembly 210 may include a sourceassembly to generate an image light to present media to user's eyes. Thesource assembly includes, e.g., a source, an optics system, or somecombination thereof.

FIG. 3 illustrates an isometric view of a waveguide display 300, inaccordance with an embodiment. In some embodiments, the waveguidedisplay 300 (may also be referred to as a scanning waveguide display) isa component (e.g., display assembly 210) of the NED 100. In alternateembodiments, the waveguide display 300 is part of some other NED, orother system that directs display image light to a particular location.

The waveguide display 300 includes a source assembly 310, an outputwaveguide 320, and a controller 330. For purposes of illustration, FIG.3 shows the waveguide display 300 associated with a single eye 220, butin some embodiments, another waveguide display separate (or partiallyseparate) from the waveguide display 300, provides image light toanother eye of the user. In a partially separate system, one or morecomponents may be shared between waveguide displays for each eye.

The source assembly 310 generates image light. The source assembly 310includes a source 340, a light conditioning assembly 360, and a scanningmirror assembly 370, described in detail below with reference to FIG. 4.The source assembly 310 generates and outputs image light 345 to acoupling element 350 of the output waveguide 320.

The source 340 is a source of light that generates at least a coherentor partially coherent image light. The source 340 emits light inaccordance with one or more illumination parameters received from thecontroller 330. The source 340 includes one or more source elements,including, but not restricted to MicroLEDs, as described in detail belowwith reference to FIG. 4.

The output waveguide 320 is an optical waveguide that outputs imagelight to an eye 220 of a user. The output waveguide 320 receives theimage light 340 at one or more coupling elements 350, and guides thereceived input image light to one or more decoupling elements 360. Insome embodiments, the coupling element 350 couples the image light 340from the source assembly 310 into the output waveguide 320. The couplingelement 350 may be, e.g., a diffraction grating, a holographic grating,some other element that couples the image light 340 into the outputwaveguide 320, or some combination thereof. For example, in embodimentswhere the coupling element 350 is diffraction grating, the pitch of thediffraction grating is chosen such that total internal reflectionoccurs, and the image light 340 propagates internally toward thedecoupling element 360. For example, the pitch of the diffractiongrating may be in the range of 300 nm to 600 nm.

The decoupling element 360 decouples the total internally reflectedimage light from the output waveguide 320. The decoupling element 360may be, e.g., a diffraction grating, a holographic grating, some otherelement that decouples image light out of the output waveguide 320, orsome combination thereof. For example, in embodiments where thedecoupling element 360 is a diffraction grating, the pitch of thediffraction grating is chosen to cause incident image light to exit theoutput waveguide 320. An orientation and position of the image lightexiting from the output waveguide 320 is controlled by changing anorientation and position of the image light 340 entering the couplingelement 350. For example, the pitch of the diffraction grating may be inthe range of 300 nm to 600 nm.

The output waveguide 320 may be composed of one or more materials thatfacilitate total internal reflection of the image light 340. The outputwaveguide 320 may be composed of e.g., silicon, plastic, glass, orpolymers, or some combination thereof. The output waveguide 320 has arelatively small form factor for a head-mounted display. For example,the output waveguide 320 may be approximately 50 mm wide alongX-dimension, 30 mm long along Y-dimension and 0.5-1 mm thick alongZ-dimension. In some embodiments, the output waveguide 320 is a 2Doptical waveguide.

The controller 330 controls the scanning operations of the sourceassembly 310. The controller 330 determines scanning instructions forthe source assembly 310 based at least on the one or more displayinstructions. Display instructions are instructions to render one ormore images. In some embodiments, display instructions may simply be animage file (e.g., bitmap). The display instructions may be receivedfrom, e.g., a console of a VR system (not shown here). Scanninginstructions are instructions used by the source assembly 310 togenerate image light 340. The scanning instructions may include, e.g., atype of a source of image light (e.g. monochromatic, polychromatic), ascanning rate, an orientation of a scanning mirror assembly, one or moreillumination parameters (described below with reference to FIG. 4 andFIG. 5), or some combination thereof. The controller 330 includes acombination of hardware, software, and/or firmware not shown here so asnot to obscure other aspects of the disclosure.

FIG. 4 illustrates a block diagram of the source assembly 310 of FIG. 3with a 1D source, the source assembly 310 outputting a scanned light, inaccordance with an embodiment. The source assembly 310 includes a source440, and an optics system 450. The source 440 is an embodiment of thesource 340 of FIG. 3. The optics system 450 includes a lightconditioning assembly 460 and a scanning mirror assembly 470. The lightconditioning assembly 460 is an embodiment of the light conditioningassembly 360 of FIG. 3. The scanning mirror assembly 470 is anembodiment of the scanning mirror assembly 370 of FIG. 3. The sourceassembly 310 generates light in accordance with scanning instructionsfrom the controller 330 of FIG. 3.

The source 440 is a source of light that generates at least a coherentor partially coherent image light. The source 440 emits light inaccordance with one or more illumination parameters received from thecontroller 330. The source 440 includes one or more source elements 420.The source element 420 may be LEDs with at least ultra-high brightness,low power consumption, and a low footprint. The source element 420 maybe, e.g., MicroLEDs, organic LEDs (OLEDs), a superluminescent LED(SLED), and organic MicroLEDs. A MicroLED is a LED that can be madesmall such that light emission area can be made to the order of a micronto a few tens of microns. For example, GaN-based inorganic LEDs can bemade orders of magnitude brighter than OLEDs with a light emission areaof few microns. The source assembly 310 of FIG. 4 may include differentembodiments of the source element 420 as discussed below with referenceto FIG. 9A-E.

In one embodiment, the source element 420 may be arranged in a concavecurved and linear fashion. For example, the source 440 may have a radiusof curvature ranging from few millimeters to few centimeters dependingon the display size and a length of few millimeters. An advantage of acurved array is that it is much easier a compact lens to have highquality image on curved surface without correcting the field ofcurvature of the lens. In alternate embodiments, the source element 420may be arranged in a flat and linear fashion.

The source element 420 emits a source light 445 to the optics system450. In some embodiments, the source light 445 may emit one or morecolors (e.g. red, green, and blue). For example, the source element 420Aemits a red source light, the source element 420B emits a blue sourcelight, and the source element 420C emits a green source light.Additionally, in some embodiments, one or more of the source elementsmay emit light in the infrared.

The optics system 450 includes a light conditioning assembly 460 and ascanning mirror assembly 470. The light conditioning assembly 460conditions the source light 445 and emits conditioned light to thescanning mirror assembly 470. Conditioned light is light conditioned forincidence on the scanning mirror assembly 470. The light conditioningassembly 460 includes one or more optical components that condition thelight from the source 440. Conditioning light from the source 440 mayinclude, e.g., expanding, collimating, correcting for one or moreoptical errors (e.g., field curvature, chromatic aberration, etc.), someother adjustment of the light, or some combination thereof. The lightconditioning assembly 460 conditions the source light 445 and emitsconditioned light 465 to the scanning mirror assembly 470.

The scanning mirror assembly 470 includes one or more optical elementsthat redirect image light via one or more reflective portions of thescanning mirror assembly 470. Where the image light is redirected towardis based on specific orientations of the one or more reflectiveportions. In some embodiments, the scanning mirror assembly includes asingle scanning mirror that is configured to scan in at least twodimensions. In other embodiments, the scanning mirror assembly 470 mayinclude a plurality of scanning mirrors that each scan in orthogonaldirections to each other. The scanning mirror assembly 470 may rasterscan (horizontally, or vertically). In some embodiments, the scanningmirror assembly 470 may perform a controlled vibration along thehorizontal and/or vertical directions with a specific frequency ofoscillation to scan along two dimensions and generate a two-dimensionalprojected line image of the media presented to user's eyes. For example,the scanning mirror assembly 470 may undergo an oscillation withpeak-to-peak amplitude of few hundreds of nanometers per second alongthe vertical direction based on the desired frequency of oscillation.The scanning mirror assembly 470 emits a scanned light 475 based on thecollimated light 465. The scanning mirror assembly 470 outputs thescanned light 475 at a particular orientation (in accordance with thescanning instructions) toward the output waveguide 320.

In some embodiments, the scanning mirror assembly 470 includes agalvanometer mirror. For example, the galvanometer mirror may representany electromechanical instrument that indicates that it has sensed anelectric current by deflecting a beam of image light with one or moremirrors. The galvanometer mirror may be configured to scan in at leastone orthogonal dimension to generate the scanned light 475. The scannedlight 475 from the galvanometer mirror represents a two-dimensional lineimage of the media presented to user's eyes.

The controller 330 controls the source 440 and the scanning mirrorassembly 470. The controller 330 takes content for display, and dividesthe content into discrete sections. The controller 330 instructs thesource 440 to sequentially present the discrete sections. The controller330 instructs the scanning mirror assembly 470 to scan the presenteddiscrete sections to different areas of a coupling element of the outputwaveguide. Accordingly, at the exit pupil of the output waveguide 320each discrete portion is presented in a different location. While eachdiscrete section is presented at different times, the presentation andscanning of the discrete sections occurs fast enough such that a user'seye integrates the different sections into a single image or series ofimages.

For example, in embodiments where the source 440 includes a linearone-dimensional array of source elements 420, the content is divided bythe controller 330 into lines where the lines are scanned out todifferent areas of the coupling element of the output waveguide 320,such that, at the exit pupil of the output waveguide 320 each of thelines are presented at a different location which a user's eyeintegrates into a single image or series of images.

FIG. 5 illustrates a block diagram of a source assembly with a 2Dsource, in accordance with an embodiment. The source assembly 310includes a source 540, and an optics system 550. The source 540 is anembodiment of the source 340 of FIG. 3. The optics system 550 is anembodiment of the optics system 450 of FIG. 4. The source assembly 310generates light in accordance with scanning instructions from thecontroller 330 of FIG. 3.

The optics system 550 includes the light conditioning assembly 460details of which presented above with reference to FIG. 4. In theembodiment of FIG. 5, the light conditioning assembly 460 outputs theconditioned light 465 to the output waveguide 320.

The controller 330 takes content for display, and divides the contentinto discrete sections. The controller 330 instructs the source 540 tosequentially present the discrete sections. The controller 330 sendsscanning instructions that cause the source assembly 310 to render lightsuch that image light exiting the decoupling element 360 of the outputwaveguide 320 scans out one or more 2D images. For example, the scanninginstructions may cause the source assembly 310 to scan out an image inaccordance with a scan pattern (e.g., raster, interlaced, etc.). Thescanning instructions control an intensity of light emitted from thesource 540, and the optics system 550 scans out the image by rapidlyadjusting orientation of the emitted light. If done fast enough, a humaneye integrates the scanned pattern into a single 2D image.

FIG. 6 illustrates an isometric view of a waveguide display 600, inaccordance with an embodiment. In some embodiments, the waveguidedisplay 600 (may also be referred to as a scanning waveguide display) isa component (e.g., display assembly 210) of the NED 100. In alternateembodiments, the waveguide display 600 is part of some other NED, orother system that directs display image light to a particular location.

The waveguide display 600 includes a source assembly 610, a sourcewaveguide 615, an output waveguide 620, and a controller 330. The sourceassembly 610 is an embodiment of the source assembly 310 of FIG. 4. Forpurposes of illustration, FIG. 3 shows the waveguide display 600associated with a single eye 220, but in some embodiments, anotherwaveguide display separate (or partially separate) from the waveguidedisplay 600, provides image light to another eye of the user. In apartially separate system, one or more components may be shared betweenwaveguide displays for each eye.

The source waveguide 615 transmits image light generated by an opticalsource. The source waveguide 615 receives the image light 655 generatedby the source 440 of the source assembly 610. The source waveguide 615reflects the received image light 655 and outputs the image light 345 toa coupling element 350 of the output waveguide 620, as described indetail below with reference to FIG. 7. In some embodiments, the sourcewaveguide 615 performs a rotation along one dimension (e.g. X-dimension)while scanning the image light generated by the source 440. The sourcewaveguide 615 includes an actuator assembly that performs the rotationof the source waveguide 615. The actuator assembly includes one or moremechanical actuators that perform a rotational motion in eitherclockwise or anti-clockwise direction at a specific frequency.

The output waveguide 620 is an optical waveguide that outputs imagelight to an eye 220 of a user. The output waveguide 620 receives theimage light 345 at one or more coupling elements 350, and guides thereceived input image light to one or more decoupling elements 360. Insome embodiments, the coupling element 350 couples the image light 345from the source waveguide 615 into the output waveguide 320. Thecoupling element 350 may be, e.g., a diffraction grating, a holographicgrating, some other element that couples the image light 345 into theoutput waveguide 620, or some combination thereof. For example, inembodiments where the coupling element 350 is diffraction grating, thepitch of the diffraction grating is chosen such that total internalreflection occurs, and the image light 345 propagates internally towardthe decoupling element 360. For example, the pitch of the diffractiongrating may be in the range of 300 nm to 600 nm.

The decoupling element 360 decouples the total internally reflectedimage light from the output waveguide 620. The decoupling element 360may be, e.g., a diffraction grating, a holographic grating, some otherelement that decouples image light out of the output waveguide 620, orsome combination thereof. For example, in embodiments where thedecoupling element 360 is a diffraction grating, the pitch of thediffraction grating is chosen to cause incident image light to exit theoutput waveguide 620. An orientation and position of the image lightexiting from the output waveguide 620 is controlled by changing anorientation and position of the image light 345 entering the couplingelement 350. For example, the pitch of the diffraction grating may be inthe range of 300 nm to 600 nm.

The output waveguide 620 may be composed of one or more materials thatfacilitate total internal reflection of the image light 345. The outputwaveguide 620 may be composed of e.g., silicon, plastic, glass, orpolymers, or some combination thereof. The output waveguide 620 has arelatively large form factor. For example, the output waveguide 620 maybe approximately 50 mm wide along X-dimension, 30 mm long alongY-dimension and 0.5-1 mm thick along Z-dimension. In some embodiments,the output waveguide 620 is a 2D optical waveguide.

The controller 330 controls the scanning operations of the sourceassembly 610 and the source waveguide 615. The controller 330 determinesscanning instructions for the source assembly 610 and the sourcewaveguide 615 based at least on the one or more display instructions.Display instructions are instructions to render one or more images. Insome embodiments, display instructions may simply be an image file(e.g., bitmap). The display instructions may be received from, e.g., aconsole of a VR system (not shown here). Scanning instructions areinstructions used by the source assembly 610 to project image light 655on to the source waveguide 615. Scanning instructions are also theinstructions used by the actuator assembly of the source waveguide 615to transmit the image light 345. For example, the scanning instructionsmay communicate the direction and frequency of rotation to the actuatorassembly. The scanning instructions may include, e.g., a type of asource of image light (e.g. monochromatic, polychromatic), a scanningrate, an orientation of the source waveguide 615, a frequency ofrotation of the source waveguide 615, one or more illuminationparameters (described above with reference to FIG. 4 and FIG. 5), orsome combination thereof. In some embodiments, the actuator assembly maybe separate from the source waveguide 615 and located inside thecontroller 330. The controller 330 includes a combination of hardware,software, and/or firmware not shown here so as not to obscure otheraspects of the disclosure.

FIG. 7 illustrates a cross-section 700 of the source assembly 610 andthe source waveguide 615, in accordance with an embodiment.

The source assembly 610 generates light in accordance with scanninginstructions from the controller 330. The source assembly 610 includes asource 640, and an optics system 650. The source 640 is a source oflight that generates at least a coherent or partially coherent imagelight. The source 640 may be, e.g., laser diode, a vertical cavitysurface emitting laser, a light emitting diode, a tunable laser, or someother light source that emits coherent or partially coherent light. Thesource 640 emits light in a visible band (e.g., from about 390 nm to 700nm), and it may emit light that is continuous or pulsed. In someembodiments, the source 640 may be a laser that emits light at aparticular wavelength (e.g., 532 nanometers). The source 640 emits lightin accordance with one or more illumination parameters received from thecontroller 330. An illumination parameter is an instruction used by thesource 640 to generate light. An illumination parameter may include,e.g., source wavelength, pulse rate, pulse amplitude, beam type(continuous or pulsed), other parameter(s) that affect the emittedlight, or some combination thereof.

The optics system 650 includes one or more optical components thatcondition the light from the source 640. Conditioning light from thesource 640 may include, e.g., expanding, collimating, adjustingorientation in accordance with instructions from the controller 330,some other adjustment of the light, or some combination thereof. The oneor more optical components may include, e.g., lenses, mirrors,apertures, gratings, or some combination thereof. Light emitted from theoptics system 650 (and also the source assembly 610) is referred to asimage light 655. The optics system 650 outputs the image light 655 at aparticular orientation (in accordance with the scanning instructions)toward the source waveguide 615. In alternate embodiments, the opticssystem 650 outputs the image light 655 to the output waveguide 320.

The source waveguide 615 is an optical waveguide. The source waveguide615 may be composed of one or more materials that facilitate totalinternal reflection of the image light 655. The source waveguide 615 maybe composed of e.g., silicon, plastic, glass, or polymers, or somecombination thereof. The source waveguide 615 has a relatively smallform factor. For example, the source waveguide 615 may be approximately50 mm long along X-dimension, 3 mm wide along Y-dimension, and 0.5-1 mmthick along Z-dimension. In some embodiments, the source waveguide 615is a narrow and long 1D optical waveguide.

The source waveguide 615 includes a coupling element 760 and adecoupling element 770. The source waveguide 615 receives the imagelight 655 emitted from the source assembly 610 at the coupling element760. The coupling element 760 couples the image light 655 from thesource assembly 610 into the source waveguide 615. The coupling element760 may be, e.g., a diffraction grating, a holographic grating, someother element that couples the image light 655 into the source waveguide615, or some combination thereof. For example, in embodiments where thecoupling element 760 is diffraction grating, the pitch of thediffraction grating is chosen such that total internal reflectionoccurs, and the image light 655 propagates internally toward thedecoupling element 770. For example, the pitch of the diffractiongrating may be in the range of 300 nm to 600 nm.

The decoupling element 770 decouples the total internally reflectedimage light 655 from the source waveguide 615. The decoupling element770 may be, e.g., a diffraction grating, a holographic grating, someother element that decouples image light out of the source waveguide615, or some combination thereof. For example, in embodiments where thedecoupling element 770 is a diffraction grating, the pitch of thediffraction grating is chosen to cause incident image light to exit thesource waveguide 615. An orientation of the image light exiting from thesource waveguide 615 may be altered by varying the orientation of theimage light exiting the source assembly 610, varying an orientation ofthe source assembly 610, or some combination thereof. For example, thepitch of the diffraction grating may be in the range of 300 nm to 600nm.

The image light 345 exiting the source waveguide 615 is expanded atleast along one dimension (e.g., may be elongated along X-dimension).The image light 345 couples to an output waveguide 320 as describedabove with reference to FIG. 3.

The controller 330 controls the source assembly 610 by providingscanning instructions to the source assembly 610. The scanninginstructions cause the source assembly 610 to render light such thatimage light exiting the decoupling element 360 of the output waveguide320 scans out one or more 2D images. For example, the scanninginstructions may cause the source, etc.). The scanning instructionscontrol an intensity of light emitted from the source assembly 610 (viaadjustments to optical elements in the optics system 650) to scan out animage in accordance with a scan pattern (e.g., raster, interlaced thesource 640, and the optics system 650 scans out the image by rapidlyadjusting orientation of the emitted light. If done fast enough, a humaneye integrates the scanned pattern into a single 2D image.

The controller 330 also controls the source waveguide 615 by providingscanning instructions to the source waveguide 615. The scanninginstructions include, e.g., an orientation of the source waveguide 615,a frequency of rotation of the source waveguide 615, etc. In oneexample, the scanning instructions from the controller 330 may cause thesource waveguide 615 to rotate in a clockwise-direction at a frequencyof 5 rpm in an orthogonal dimension (e.g. X-dimension) that causes therendering of one or more discrete sections in the content for display.

FIG. 8 illustrates a block diagram of a source assembly 810 with the 1Dsource, in accordance with an embodiment. The source assembly 810includes a source 840, and an optics system 850. The source 840 is anembodiment of the source 440 of FIG. 6. The optics system 850 is anembodiment of the optics system 450 of FIG. 6. The source assembly 810generates light in accordance with scanning instructions from thecontroller 330 of FIG. 6.

The optics system 850 includes the light conditioning assembly 460details of which presented above with reference to FIG. 4. In theembodiment of FIG. 8, the light conditioning assembly 460 outputs theconditioned light 865 to the source waveguide 615.

The controller 330 takes content for display, and divides the contentinto discrete sections. The controller 330 instructs the source 840 tosequentially present the discrete sections. The controller 330 sendsscanning instructions that cause the source assembly 810 to render lightsuch that image light exiting the decoupling element 360 of the outputwaveguide 620 scans out one or more 2D images. For example, the scanninginstructions may cause the source assembly 810 to scan out an image inaccordance with a scan pattern (e.g., raster, interlaced, etc.). Thescanning instructions control an intensity of light emitted from thesource 840, and the optics system 850 scans out the image by rapidlyadjusting orientation of the emitted light. If done fast enough, a humaneye integrates the scanned pattern into a single 2D image. Thecontroller 330 instructs the source waveguide 615 to perform a scanningoperation in an orthogonal dimension that renders the display of one ormore discrete sections in the content for display.

Turning now to a discussion of source element geometries andorganization, FIGS. 9A-D depict various layouts for source arrays. Inthe source arrays, a die represents a source element. Additionally, thedies in the source arrays have a square emission area. The squareemission area allows for the dies to be densely packed together whichfacilitates a reduction in form factor of a source array. In alternateembodiments, the dies may have other shapes (e.g., rectangular,hexagonal, circular, etc.). Accordingly, the dies in the source arrayshave a corresponding shape for the emission area.

FIG. 9A illustrates an array 910 of adjacent dies, in accordance with anembodiment. The array 910 represents an embodiment of the source 440 ofFIG. 4. The array 910 includes a plurality of dies 915 that are placedin a one-dimensional array. In some embodiments, the dies may bearranged in a linear and flat array along one dimension. In alternateembodiments, the dies may be arranged in a linear and curved array alongone dimension. The dies 915 are monochrome. In some embodiments, all ofthe dies 915 emit light in the same range (i.e., all same color). Inalternate embodiments, one or more of the dies 915 in the array 910 emitlight in ranges different from other dies 915 in the array 910.

FIG. 9B illustrates an array 920 that includes an optical isolator 925,in accordance with an embodiment. The array 920 is the array 910 of FIG.9A, but includes an additional optical isolator 925 that reduces opticalinterference with adjacent source elements. Each of the dies 915includes four outer edges (sides), and at least two sides of each die915 is in contact with the optical isolator 925. The optical isolator925 may be composed of, for example, Aluminum, some other materialmetal, some other material that reduces optical interference withadjacent source elements, or some combination thereof. The opticalisolator 925 may be formed around dies 915, e.g., as a coating, film,etc., during the manufacturing process. In the embodiment of FIG. 9B,the optical isolator 925 surrounds the two opposite sides of the die915.

FIG. 9C illustrates an array 930 with non-adjacent dies, in accordancewith an embodiment. The array 930 is functionally similar to the array910 of FIG. 9A, but includes dies 915 that are placed in a non-adjacentfashion. The non-adjacent arrangement of the dies 915 helps to avoidcross-talk (optical interference) between the image light output by eachof the dies 915. In the embodiment of FIG. 9C, the optical isolator 925surrounds the die 915 in at least three of the four sides.

FIG. 9D illustrates a stacked array 940 of three columns of 1D array, inaccordance with an embodiment. The stacked array 940 is structurallysimilar to the array 920 of FIG. 9B. In some embodiments, the 2D array940 includes a plurality of arrays 910 arranged in a linear fashion,wherein an optical isolator 925 is between adjacent arrays 910. Theaggregate structure of alternating array 910 and the optical isolator925 form a 2D array. In FIG. 9D, the 2D array 940 includes three arrays910, however, in other embodiments the stacked array 940 may includesome other number of arrays 910. The arrays 910 may all emit light inthe same range (i.e., all same color). In alternate embodiments, one ormore of the arrays 910 in the stacked array 940 emit light in rangesdifferent from another array 910 in the stacked array 940. For example,there may be three arrays 910, one of which emits red light, one ofwhich emits green light, and one of which emits blue light. In anotherexample, at least one of the arrays 910 emits light in the infrared. Insome embodiments, the stacked array 940 may include a control circuitthat performs the controlling of at least the color intensity,brightness, and duty-cycle of operating each of the individual arrays910 inside.

FIG. 9E illustrates a 2D sparse array 950, in accordance with anembodiment. The 2D sparse array 950 is an array of dies 915 spaced apartto form a sparse array along two dimensions. In some embodiments, the 2Dsparse array 950 includes a plurality of arrays 960 arranged in a linearfashion, wherein each of the dies 915 in the plurality of arrays 960 isin contact with the optical isolator 925 on all four sides. In FIG. 9E,the 2D sparse array 950 includes four arrays 960, however, in otherembodiments the 2D sparse array 950 may include some other number ofarrays 960. In some embodiments, the 2D sparse array 950 includes aplurality of arrays 960 that are located at one or more distance ofseparation. For example, the 2D sparse array 950 includes a firstdistance of separation of 10 microns between a first array 960A and asecond array 960B, and a second distance of separation of 50 micronsbetween the second array 960B and a third array 960C, respectively. In adifferent embodiment, each of the dies 915 in each of the arrays 960 hasone or more distance of separation. For example, a die 915A in the array960 may be located at a distance of separation of 5 microns from a die915B in the array 960, and a die 915C in the array 960 may be located ata distance of separation of 50 microns from the die 915B. The arrays 960may all emit light in the same range (i.e., all same color). Inalternate embodiments, one or more of the arrays 960 in the 2D sparsearray 950 emit light in ranges different from another array 960 in the2D sparse array 950. Each of the dies 915 includes four outer edges(sides), and at least two sides of each die 915 is in contact with theoptical isolator 925. The 2D sparse array 950 includes the same numberof dies 915 as the array 920 of FIG. 9B. In some embodiments, the 2Dsparse array 950 is an embodiment of the source 540 of FIG. 5.

Turning now to a more detailed discussion of source design, to calculatehow may MicroLEDs should be in a 2D array to achieve a given brightness,one begins with an average brightness of the MicroLEDS (e.g.,approximately 500 k nits). Assuming a Lambertian emission pattern forMicroLEDs, and the max MicroLED intensity at die location is 350 W/cm²,and the three colors used for display are 450 nm, 530 nm, and 615 nm(there is challenge to integrated packed array RGB on one chip). Asingle RGB group (i.e., pixel that includes a source element that emitsred light, a source element that emits green light, and a source elementthat emits blue light) can emit an average of 8.4×108 Lumen/m² lightwhen RGB pixel power densities are 350 W/cm², 310/cm², and 220 W/cm²,respectively. The average brightness of over a single RGB group is2.66×10⁸ nit. Note that the display brightness may be reduced from thisvalue due to scanning. The number (n) of RGB pixel groups needed to havea projector of an average brightness (B) is a linear function of thenumber of display pixels (N), and are related via the followingequation:

$\begin{matrix}{n = \frac{B}{\left( {2.66 \times 10^{8}} \right)/\left( \frac{N}{3} \right)}} & (1)\end{matrix}$where B is the average brightness (e.g., 500 K nit). For example, in thecase of a 500 k nit projector, n≈6.3×10⁻⁴ N.Additional Configuration Information

The foregoing description of the embodiments of the disclosure has beenpresented for the purpose of illustration; it is not intended to beexhaustive or to limit the disclosure to the precise forms disclosed.Persons skilled in the relevant art can appreciate that manymodifications and variations are possible in image light of the abovedisclosure.

Finally, the language used in the specification has been principallyselected for readability and instructional purposes, and it may not havebeen selected to delineate or circumscribe the disclosed subject matter.It is therefore intended that the scope of the disclosure be limited notby this detailed description, but rather by any claims that issue on anapplication based hereon. Accordingly, the disclosure of the embodimentsis intended to be illustrative, but not limiting, of the scope of thedisclosure.

What is claimed is:
 1. A scanning waveguide display, comprising: a lightsource including a plurality of source elements that are configured toemit an image light that is at least partially coherent; a scanningmirror assembly configured to scan the image light as scanned imagelight at least along one dimension to particular locations in accordancewith scanning instructions; an output waveguide including an input areaand an output area, the output waveguide coupled to receive the scannedimage light emitted from the scanning mirror assembly at the input area,expand the scanned image light at least along two dimensions, and outputthe expanded image light from a portion of the output area, the locationof the portion of the output area based in part on a direction of thescanned image light output from the scanning mirror assembly; and acontroller configured to generate the scanning instructions and providethe scanning instructions to the scanning mirror assembly.
 2. Thescanning waveguide display of claim 1, wherein the plurality of sourceelements form a one-dimensional array and are configured to emit theimage light, and each of the plurality of source elements corresponds toa line in an image output by the scanning waveguide display.
 3. Thescanning waveguide display of claim 2, wherein the one-dimensional arrayis curved.
 4. The scanning waveguide display of claim 1, wherein theplurality of source elements are placed in a sparse two-dimensionalarray and are configured to emit the image light, and each of theplurality of source elements corresponds to a portion in an image outputby the scanning waveguide display.
 5. The scanning waveguide display ofclaim 4, wherein the sparse two-dimensional array comprises at least afirst source element and a second source element, the first sourceelement emits light at a first range of wavelengths, the second sourceelement emits light at a second range of wavelengths that is differentfrom the first range of wavelengths.
 6. The scanning waveguide displayof claim 1, wherein the scanning mirror assembly comprises at least agalvanometer mirror.
 7. The scanning waveguide display of claim 1,wherein the scanning mirror assembly comprises at least a MEMS mirror.8. The scanning waveguide display of claim 1, wherein the plurality ofsource elements each emit light of a same wavelength.
 9. The scanningwaveguide display of claim 1, wherein the plurality of source elementsinclude at least one source element to emit light in a different rangeof wavelengths than another source element of the plurality of sourceelements.
 10. The scanning waveguide display of claim 1, wherein theplurality of source elements are selected from a group consisting of: alight-emitting diode (LED), a MicroLED, an organic light-emitting diode(OLED), an organic MicroLED, and a superluminescent light emitting diode(SLED).
 11. The scanning waveguide display of claim 1, wherein eachsource element of the plurality of source elements includes a pluralityof sides, and for each source element: at least two of its sides are incontact with an optical isolator that reduces optical interference withadjacent source elements.
 12. The scanning waveguide display of claim11, wherein for each source element: the optical isolator is in contactwith at least three of its plurality of sides.
 13. A scanning waveguidedisplay comprising: a light source configured to emit an image lightthat is at least partially coherent, the light source comprising aplurality of source elements that form a one-dimensional array and areconfigured to emit the image light, and each of the plurality of sourceelements corresponds to a line in an image output by the scanningwaveguide display; a light conditioning assembly configured to conditionthe image light from the plurality of source elements; and a sourcewaveguide including an entrance area and an exit area, the sourcewaveguide configured to receive the conditioned image light from thelight conditioning assembly at the entrance area, expand the conditionedimage light in at least one dimension, and output the expanded imagelight from the exit area.
 14. The scanning waveguide display of claim13, wherein each source element of the plurality of source elementsincludes a plurality of sides, and for each source element: at least twoof its sides are in contact with an optical isolator that reducesoptical interference with adjacent source elements.
 15. The scanningwaveguide display of claim 14, wherein for each source element: theoptical isolator is in contact with at least three of its plurality ofsides.
 16. The scanning waveguide display of claim 13, wherein theone-dimensional array is curved.
 17. The scanning waveguide display ofclaim 13, further comprising: an output waveguide including an inputarea and an output area, the output waveguide coupled to receive theexpanded image light emitted from the source waveguide at the inputarea, and output the expanded image light from a portion of the outputarea, the location of the portion of the output area based in part on adirection of the expanded light output from the source waveguide; and acontroller configured to generate the scanning instructions and providethe scanning instructions to one or more actuators associated with thesource waveguide.